Apparatus for mixing and blending fluids



DC 9, 1947. G. GQscHM-IDT 2,432,175

APPARATUS FOR MIXING AND BLENDING' FLUIDS Filed oct. 16, 1944 2 sheets-sheet 1 .Fil-

INVENTOR @fa/Q65 G Jaw/w07',

ATTORN EYS Dec. 9, 1947. G. G. scHMlDT APPARATUS FOR MIXING AND BLENDING FLUIDS 2 Sheets-sneet 2 Filed oct. `16. 1944 INVENTOR G50/Q65 Jam/m7; g BY Mame@ Patented Dec. 9, 1947 APPARATUS FOR MIXING AND BLENDING FLUIDS George G. Schmidt, Forest Hills, N. Y. Application `October 16, 1944, Serial No. 558,923 13 claims. (01.259-951 This invention relates to apparatus for mixing and blending fluids, and particularly to such ap- -paratus as, for purely illustrative purposes, are particularly adapted to mixing and blending paints and the like.

In the prior art of mixing, it has been common to provide a tank as a mixing receptacle into which the ingredients are poured or otherwise disposed or placed, with a frequent stratification of materials into layers of different materials or densities which require intimate 'mixing to convert the heterogeneity of the mass into useable homogeneity. In one class of mixing devices a closed circulation of the fluid has been provided sucking the liquid into an openmouthed delivery pipe at and generally flush with the bottom of the tank, forcing it through the pipe to a pump, and discharging the output of the pump into the tank at the top thereof. This system establishes a vortex ap-preciably smaller in diameter than the tank and with poor and incomplete mixing.

In another form of mixingdevice the tank has been provided with a rotary or otherwise moving poweractuated mechanical agitator. This is in the form oi impellers, propellers, or paddles, or the like. This power agitator has been used alone in some cases and in others has been coupled with and superposed upon the closed circulation through the return ow device mentioned. In many cases, areas or zones of the materials are found to remain in the tanks without being mixed, and the intimacy., of ultimate mixing is sometimes somewhat lacking. Moreover, the frictional effects produced introduce excessive heat into the mass which must be controlled, and, of even greater import, such heat conversion represents a direct loss of power that is expensive and undesirable. The uid circun lation with the open pipe intake is marked by a rapid acceleration of the fluid adjacent to but outside of the actual intake pipe, resulting in a vortex in the body of liquid in the tank which limits the area or total Zone of materials being mixed. Both the recited circulation and the mechanical agitation introduce such factors of rapid acceleration in the main body or mass oi the material in the tank that eddy formation and turbulence creation are inevitable, with losses of energy and. improper ultimate mixing. Moreover, the turbulence created in the tanks is such as to keep the upper surface of the materials in a state of such unrest as to necessitate a cover as a splash receiver, which complicates the tank manipulations and increases its cost as well as the processing cost.

It is among the objects of this invention: to reduce the power requirements for mixing apparatus; to provide a mixing system which obviates the necessity for a mechanical agitator in a tank; to provide a circulating system for tanks with means for securing rapid acceleration of the fluids in the intake pipe and means while maintaining slow velocities in the body of liquid; to provide a hydraulic agitatng system by which the intake portion of the system exerts an attraction to particles at remote portions of the mass in the tank unrelated to a vortex attraction; to provide a mixing hydraulic circulating system by which movement of the particles in the mass relative to adjacent particles is at such a slow rate as to preclude such shearing action as would establish eddies and such similar manifestations of turbulence; to provide a mixing system for fluids in which the entire mass of liquids is guided into an intake pipe through convergent means by which slow ilow movements in the tank are converted into accelerated now within the guiding means and intake whereby intimacy of scrubbing contact is established without having any appreciable turbulence appear in the tank itself; to provide a plurality of frustums oi cones in nested convergent relation with means 'for drawing liquids into the spaces between the cones in an accelerating flow to delivery into an intake pipe; to provide a plurality of such truncated cones in nested spaced convergent relation to intermediate quasi-helical vanes and with means for drawing liquids through the cones and spaces between the cones whereby the liquid accelerating in its flow through one cone is given a whirl in one direction while the liquid passing through and accelerating in its flow adjacent thereto is given a whirl in the opposite direction so as to force intimate mixing swirling turbulent flow through the com mon delivery of the cones to enhance the intimacy of mixing of the constituents to increase the eiciency of the mixing process; to provide in a mixing apparatus a critical arrangement of cones for intake of fluid for re-circulation whereby to eiect a reaching out into heterogeneous regions in a body of fluid by means oi controlled velocity vectors within the body of the fluid; to provide a hydraulic mixing system for liquids whereby a selection of heterogeneous zones of liquid for ow into the circulating stream is controlled so that turbulent flow in the body showing by respectively dotted,v dashed and-l dotted, and full lined arrows, the flows into the..v mixing unit at different levels.

Fig. 2 represents a plan ofjtlfeitankandhydraulic system of Fig. l showing by concentric;v

series of arrows of different visual asp eclls.-sllr. 15 ,q

rounding the intake unit the direction of`sub stantially helical flows into thefseyerali'moilthsej when guide varies are provided in association withthe cones in one embodiment thereof.

Fig. 3 represents an elevation of a tank with amodied form'of dischargeassemblye for returnsing the flow to the tank.

Fig: 4- represents' an vertical Atransverseesection throughthe `assembly of-v truncated' cones-f of-'theV inta-ke `unit vand-fthe inta-ke connectorz' of the'liy-m 25.:V

draulic system',` according-atofone=i`rm` of fthe'vina vention.

Fig: 5l represents y'as plainoff*tl'1e1coneassembly:r dischargesor-'intake lof Figs 4;'sliowingfby respecttive, dotted, dashed and dotted," andlfull'lined arrows the direction' of`v opposingsubstantiallyf helica1 ilows'leadingintol theacommon dischargeV chamber `of the 'uniti in' different-mouths ati dif ferent levels.

Fig;,6 represents-a fragmentary plan'offa--modiv 35A fied form of intakeunit in-whichthe-initialflowsr into: therespective convergent vlmouths are=radial of the -unitV with short-1 blades` or vanes-Aw-itl'iin-` the-unit spaced4 from'the mouthsithereoff 11o-im partA respectively clockwiseL or'y counterclockwise` whirls to the flows-enteringthefrespective mouths.:` forenhancing; mixingfv within the/unit` Fig. 7 represents a^transverse1verticalv section: through the unit-of Fig.; 6?

ReferringtdFigs. 1 and2 it'w-illbefobserved. that Ithe tank ID has preferably.: an' open -topz I l.' and is p rovided, pref erably;` sub'stantially;centrallyf.l of thetank I [lj-with a compound :conef intake'unit. l2', to bedescribed=in detail l hereinafter.. The'. intake Y unit leads f to' anl intakeL pipe.y 13;. whichg., purely illustrativel-y; willor1 may be` of approxi mately 2" diametenwhen the :tankzissof the v:pord'eri of1=1000 gallons capacity.: The intakepipesl3'ileads'.v through aheat exchangeunitilll forteitherrheate ingfor 'cooling the materials:ilowingfthroughxine 55 takepipe- I 3,4 and f delivers into 4a-..pump.: unitzil 5.1. including or having a. power.- s0urce.f1such:.as.-a,. motor 16.1 'I'l'ie-discharge-from thepurnnI5lleads.:` through suitableA connections |91' tof preferably.' three-iet discharges=respectively Il;` lilra-.IiciiZlliv suitably disposed within theltank lIJ.;preferably.` at different levels-below the. level j ofir the. upper.- surfacev of the Aliquid :masszin :the .tankzandgwth two atleast.enteringfthe'tank atrespecti-vely Wdifferent anglesrelative .tothefvertical axistherof 65 so Vas l. to assist.` in'Y generally.1 agitatingf.r the mass.A in the tank... The=dischargeipipeszfor'the `dis.-` charge jets are, illustratively;- .for the-tank canile-v ity. ancii intake f. pipe ;size used f as an'- illustrative.- case, of th'emrder;offapproximately-lf indiame-` ter.'

As shown inFig. 3,.the dischargejets .forthe system maycomprise. merelyYY twoinnumber. Aon the ends -of .the.respectivadischargepipes2| and." 22 as shown. For illustrative purposes. these also may be of the order of approximately 1" in diameter. Obviously, if desired, the discharge may comprise a single nozzle, or any desired number greater than the three shown in Fig. 1.

'I'he fundamental structural feature by which the highly efficient mixing and blending derivable from the invention herein is obtained, is an intake d evice or unit formed illustratively of sheet metalorrplastics yor the like; of the general character illustrated in one embodiment in Figs. 4 and 5. The oor of the tank I0 is indicated at 23 with an orifice 24 within which.the intake unit liquidimixeritmbe'described is sealed in any conventional or suitable manner. Essentially, the liquid mixing andblending unit comprises at least two open-'ended truncated conical members and afcommcn vdeliveryconduit associated therewith. In the'illustrative form of unit under discussion, ahollow open ended small truncated cone 25 is provided having a vertical axis with which the entireunit isfconcentric.V Cone; 25- lsspreferably formediwith: ai'wall; leading; fromi thef, upper 1' en'.- trancevorfintakexmouth:25 tot-alower discharge:

outlet -2T at a'relatively acute angle to theyerti'cal.,v

axis of the @one compared to otherfconesgofgthea unitzi. The; cone y2 5 is-:directed Pupwardly -t o wardla central zone-offinuence in the tank'and isheld: in spaced.; relation to the next truncated open ended,` obtusecone member 28' in anyY suitable:

Way.;l and; preferably, although not'4 necessarily; essentially; byiV a `series of. whirl-inducing vanesf` to be described. Thevertical axis of thefconev 2-fasfnoted is coincident with theaxis ofthe. conez25, but the upper end ormouth 30'fthereof isibelow the level of; the mouth.261-of; cone-f25;. but gbeing. *ofapprec'iablyI greater-diameter; than:

cone-25-`extends laterally therebeyond throught-.-

outgtherperiphery: of the latter; to Vdefine between'. the mouths. Zifand 30'fafconvergent entrance-ori.

.inta'ke-passageh the medianzline or cone linet ofgwhich-projects upwardly into asecond'zone Yof.

influence concentric withand spaced fromithe;

central vzone of influence of'cone- 25. The second conef28has `alower discharge mouth `32 of muchv `'greaterfdiameter than andspaced slightly-below,-

the smaller-mouth27 of the upper cone. Ther conev 28inaturn is-suppcrted in-any desired man-,-p ner.- as; byl whir1inducing..vanes to `be described.

relative-to a lower plate 33.Y Plate33 isarranged f to overlie thefoor 23 in lsuch close relation preff erably.- as.v to interpose` no appreciable restraint, togowialong-thev-iioor of the tank, andmerges-V into the discharge-pipe 34 by a mouth 35 arranged.-

slightly below mouthy 32of1the second cone-and,.- of greater diameterl than saidlast mentioned mouth.:V It will be observed that plate-33 vand sec-.-M

ond-.cone 28 establish an inwardly convergent en trancefpassage fleading into the unit; Them-edian cone line of passage 36 projects upwardly laterally-,into-a third zone of influence concentrici withl andspacedfrom yboth the-central and secr ond zones; The discharge pipe 3ft-and its mouth the spaced mouth 32 and the spaced mouth. 2'Ifali vare-located-in and define, a common mixe ingpassagee'linto which alliof the conical :.pasf4 sagesudischargeor deliver liquid entering the re-` spectiveentrances or mouthsin. an accelerated.,

high velocityv discharge.

The broad cone arrangements of intake unit4 IZare-,identicalin Figs. 4, 5, 6 and 7 and .the following description of their operations will be, understood to be directed to all four gures. This is because under the broadest aspects of the invention the.whir1inducing blades maybe' omittedwhile still attaining a useable eciency" of mixing. As each of the passages through the unit are convergent from the large entrance to the smaller delivery opening located in the common internal mixing chamber, it will be clear that the flows in and about or adjacent to the mouths in the tank and flows along the median cone lines of the zones of influence in the tank spaced from but directed toward the intake unit are at relatively slow velocities compared with the accelerated rate of flow at the discharge from each passage into the common mixing passage 31 and into the pipe I3. It is probable that the pressure drop at the several mouths 21, 32 and 35 relative to the pressures at the entrances to the several converging passages mutually conduce toward the acceleration of the ows through the several passages.

Assuming that the tank is at the proper level with liquids to be mixed, such, illustratively only, as paint, for example, and with the entire hydraulic system properly filled and with the intake unit comprised of mere cones, apart from blades or vanes, the motor I6 is started and the pump I5 begins to move the liquid from intake pipe I3 through the pump and into the connecting system I9 for jet discharge from the nozzles I1, I8 and 20, back into the tank I0. This circulatory movement causes such dierential pressures on the liquid in the tank and that in the discharge pipe I3 that there is forthwith a iiow from and relative to the several zones disposed in concentric spaced relation in the liquid in the tank as focal centers of attraction on one side at least of zones of less attraction with which varying di'erential ows are to be established into the several mouths of the unit. These flows are marked by relatively slow velocities in the tank so that while with reference to the material in the tank on each side of the focal line or cone line of the passages into the unit, diierential flows toward unit I2 are secured, to enhance mixing in the tank, account is taken of the high viscosity of the materials to establish such small or low diierentials in ow rates that shearing stresses between contiguous particles traveling toward the cone mouths at diierent velocity rates is reduced to such a negligible point that practically no eddies or turbulences appear in the liquid in the tank itself. At the same time that more or less gentle but thorough mixing is occurring in the tank, however, the slowly moving materials entering the respective mouths of the unit I 2, are, within the mixing unit, given a rapid acceleration and pass into the common discharge outlet, and the intake pipe I3 at very high veloci ity. It will be apparent that there will be three initially at least relatively independent relatively concentric columns of liquid passing into the cornmon chamber 31, and due to impingement and contact they will rapidly be transformed into a common merging mixed single stream entering pipe I3, as a function of which, and of the passage through the pump, the materials are placed under high turbulence and intimate scrubbing action which establishes a most intimate mixing and blending. The eventual projection through jets I1, I8 and 2D, removes the turbulence effects of the scrubbing by projecting high velocit-y discharge into the slow velocities in the tank, with components which are already highly mixed. It will be obvious that it takes but a comparatively short time for this hydraulic circulation alone to accomplish a most eicient and intimate blending and mixing of even very diverse materials of appreciably different densities and of degrees of viscosity or uidity.

In further explanation of the energetic mixing that occurs in the common chamber 31 of unit I2, it will be apparent that there will be initially a solid column of high velocity discharge from mouths 21 and 32 and possibly 35, but of these the only one which is directly vertical is the center one passing through cone 25. The ow from passage 3| through mouth 32 has a lateral component causing transverse impingement against and intimate mixing with the vertical co1- umn from mouth 21. Similarly, the low through passage 36 is possessed of a much greater lateral component to impinge against and thoroughly mix with the compound stream from mouths 21 and 32. The ultimate result is complete scrubbing and intermixing in a common single stream emerging from spout 34 into pipe I3.

Mention has been made of the fact that the means for supporting the cones relative to each other inl Figs. 4 and 5 may, if desired, be by means of whirl-inducing vanes or blades, and one form of theseis shown in these gures. The blades need not be actual supports, of course, as it is merely necessary within the contemplation of the invention that liquid ilowing through one ,or more of the several passages in the unit be given such rotative component as to assist and enhance the intimacy of mixing in the common chamber 31. Thus, as shown in the noted gures, the cone 25 may be provided with a series, say, illustratively, of four sloping generally arcuate blades 38 arranged generally in the form of a helix so that liquid flowing axially downwardly will be given a rotative component, which, illustratively, will be clockwise, so that liquid iiowing at high velocity from the delivery mouth 21 of the cone 25 will have a clockwise component as indicated by the arrow in full lines in all iigures. Cone 25 and cone 28 will have a series, say, also illustratively, of four inclined blades or vanes 40 arranged to impart a rotative component to the accelerated low passing out of the lower mouth 32 thereof as indicated by the dot and dash arrow in all figures. Preferably, the helical disposition of the blades 40 is such as to impart a counterclockwise component of rotation to the liquid flowing through passage 36 provided that the flow from cone 25 was clockwise. Finally, extending between the floor-disposed element 33 and the cone 28 is the series of arcuate inclined blades or vanes 4I, illustratively also, four in number, and which impart a clockwise whirl or component to the ow descending into the pipe 34 over the edge of mouth 35 as indicated in dotted arrows in all gures. It is preferable with this form of the invention that the helical blades be so disposed as to work on the entire body of liquid in the convergent spaces, starting at or adjacent to the mouth of the respective openings or entrances, and the effect of this is to start a helical whirl in the body of liquid in the tank adjacent to but external of the intake unit. This has the advantage of setting the liquid adjacent to one level of the intake unit to whirling in one direction in a small simulation of a vortex in a counter direction so as to start a further intimate admxture of the liquid in the tank itself adjacent to the unit by supplemental differential flows. While this is desirable under certain conditions of materials and times, in certain cases it is undesirable that there be any angular relative ows in the tank itself nor any other than those occasioned by establishment of a mul- 7 tiplicity of streams lof.I varying -velocitiesenwing toward and into the unit, as this 'latter isfmore gentle and` vless conducive -to the formation of eddies and the. like'vvithin the 'tankiitselh lIn. a further `modiicationgall Fflows Within the tankareradial of the-unit fintheffloor,` while still obtaining the benefits. of the` enhancedscrubbing action of the im'pinging intersecting counter ows within Athe common` chamber 31 ofthe unit, and this :is shown jin-Figs. 6 andi?. In lthis Vformvcf theinvention, as noted, the constrictionzof cones, and the mouths .for entrance and vdischarge are the 'same as and bear the same reference char-` actersJas-the 'analogous cones ofthe Figs. 41 and v5. Inthis case, however, the inner surface of the topzcentral cone 25;has1.an entrance farea: of Yc onducting lsurface 42 into which the liquidi-lows radially ofthe unit symmetricallyaboutwthe vperiphery of the mouth'` y26 Lof .the cone. Then. Athe lower vinternal surface-of Vthe coney 25, in'. arrelatively short bottom area 43,. adjacent to.- mouthl 21', has. `a :plurality of 'short inclined blades .or vanesf 4'4 varranged to impart a Irotational Acom-- ponent to the flowing fstream moving axially thruughthecone 25. .Thiszhasithefadvantageof reducingrthe friction: developed -in ,the "ow; and pern'iitting` straightiiradial' "flows intoithe central cone-while still imparting the 'desired whirl to the descending flow.. Similarly, the next more obtuse icone "28 a'carri'es: 'on its inner lower :surface bei'owa, bare area 391ap1uralityfof inclined short varies or 4blades l45,. by which, after.-a `:straight untwisting -radial fentrance :into `.passage '3 if, a rotational component is imparted to :the flow. Blades vlfarepreferably reversely inclined so that the .imparted rotational component is preferably counterto that ifrom cone A25'. Finally, -a similar bare area inducing radial' flow'- is provided on surface 33, as at '45, while adjacent ftofrth'e `exit or discharge opening 35 thereof there are the respective inclined vanes or blades l'l ofla series arranged toimpartza rotational componentto the liquid passing into thefcommon dischargezpassage 3flthrough the=entrance or I,passage 316.

It Will be clear that if desired the blades or vanes of any length can be equally `wellattached tothe under side of any cone as well as-on the inner surface. Furthermore, it-Will' be appreciated that the iiow through the central cone 25 can be a straight Vvertical ovvwithouta rotational Vcomponent while the flow through the other channelsY or vpassages 1can be givenrotational ows .in relative opposition. Further, it will be appa-rentthat-if'one-descending'columnin chamber -3fl only is given a, rotationalcomponent-enhanced mixing will ensue.

In conclusion, it will be evident that an improved mixing apparatus and process has been created herein `by which agitation within 'the tank as 'by differential ii'ows is 'kept within `the bounds of safety consonant withReynoldsnumbers-for lsuch viscousiiuids as are contemplated herein to utilize most eihciently the mixing-and blending 4characteristics of such diierential -fiows -Within the tank or container, while the added high'accelerations and intimate scrubbing', mixing and 'blending occurring within the unit and within the vconiines of thehydraulic system without undue accelerations within the body of liquid, Will-be. appreciated. Furthermore, the advantages ofthe enhancement of the intimate mixing within the unit by having rotational components imparted tothe flows, and especially those-.imparted in 'relative opposition Within` the unitwill; be appreciated., The Vfact that manynnodications and changes can be made within the teachings ofthefinvention without departing Yfromthe spirit thereof and within the scope of the appended claims willalso be-appreciated, and such changes are to4 be construed as within the scope of the.v said invention.

Having thus described my invention, I claim:

1. A mixing device for liquids comprising aY plurality of substantially concentric angularl-y divergent open-ended axially spaced nested truncated cones arranged to be relatively immersed'in a body of liquid, with the large ends thereof arranged to receive slowly flowing streams of liquid in the said body thereof, and the small ends thereof delivering rapidly owing streams Aoi liquid-into a common delivery conduit leading, from the said body of liquid.

2. A mixing device for liquids in a tankicomprising ahydraulic circulating system having an intake-in the tank and having an outlet discharging into `the tank, said intake comprising a stationary plurality of open-ended outwardly relatively divergent axially spaced truncated cones leading to a common mixing chamber `substantiallyconcentric with the cones, andmeansi establishing communication between the chamber and the -hydraulic system.

.3. A mixing device for liquids in a tank com-- prising the intake for a stationary'hydraulicsys-y tem, comprising a, plurality of substantially concentricaxially spaced nested outwardly relatively divergent open-ended truncated coneseach'hav` ingone end-comprising an entrance andthe'other end comprising a discharge outlet and, the'discharge outlets of which are directiedinto a common xed discharge outlet.

4. A mixing device for liquids in va tank comprising the intake for a hydraulic system, comprising a plurality of `nested open-ended `nonparallel Vtruncated cones the discharge outlets of which are directed into a common discharge outlet, and means associated with the space between ad-jacent cones for imparting a rotational component to liquids passing between saidcones.

5. A mixing' device for liquids in'a tank comprisinga stationary intake unit for-a circulatory systemy for the tank comprised of a pair of openended non-parallel truncatedsubstantially concentric cones in spaced relation with the open upper ends at diierent levels and having different sizes of non-divergent entrances forming a plurality of passages into a relatively xed common Imixing chamber, and means defining such mixing chamber.

6. A mixing device for liquids in a tank comprising an intake unit for a circulatory system for-the tank comprised of a pair of open-ended non-parallel truncated cones in spaced relation with the open upper ends at diierent levels and having different sizes of entrances forming a plurality of passages into a common mixing chamber, means defining such mixing chamber, and blades for imparting a whirl to liquids-passing into the mixing chamber adjacent one of said cones.

'7. A mixing device for liquids in a tank comprising an intake unit for a circulatory system for the tank comprised of a pair of open-ended truncated cones in spaced relation with the open upper ends at different levels and having diierent sizes of entrances forming a plurality of passages into a common mixing chamber, means defining such mixing chamber, and blades for imparting counter whirls to the streams passing adjacenteach of Vtwoof the said cones respectively to generate mixing turbulence in said mixing chamber.

8. A mixing device for liquids in a tank comprising a plurality of substantially concentric axially spaced guiding devices, the spacing of the guiding devices forming a plurality of inwardly convergent substantially conical passageways, the entrances to the several passageways being respectively of different sizes and located at different levels, means iixed relative to the guiding device and such tank dening a common passage for all of the passageways into which they each discharge fluids owing into the entrances thereof.

9. A mixing device for liquids in a tank comprising a plurality of guiding devices, the guiding devices having a plurality of inwardly convergent substantially conical passageways, the entrances to the several passageways being respectively of different sizes and located at different levels, means defining a common passage for all of the passageways into which they each discharge iluids flowing into the entrances thereof, and means associated with one of the passageways for imparting a rotational component to uid passing through it.

10. A mixing device for liquids in a tank comprising a plurality of guiding devices, the guiding devices having a plurality of inwardly convergent substantially conical passageways, the entrances to the several passageways being respectively of diiferent sizes and located at different levels, means dening a common passage for all of the passageways into which they each discharge fluids flowing into the entrances thereof, means associated with one of the passageways for imparting a rotational component to fluid passing through it, and means associated with another of the passageways for imparting a rotational component to the fluid passing through it.

11. A mixing device for liquids in a tank comprising a plurality of guiding devices, the guiding devices having a plurality of inwardly convergent substantially conical passageways, the entrances to the several passageways being respectively of different sizes and located at different levels, means defining a common passage for all of the passageways into which they each discharge uids flowing into means associated with one of the passageways for imparting a rotational component to fluid passing through it, and means associated with another of the passa-geways for imparting a rotational component to the fluid passing through it counter to the rotational component imparted to the rst mentioned fluid stream.

the entrances thereof,

12. A mixing system for liquids which comprises a receptacle for the liquids, means for circulating liquid at a high rate of flow from an entrance at one part of the receptacle to discharge into another part thereof, and means for securing relatively slow differential flows in the liquids in the tank passing toward said entrance to the circulating means whereby shearing stresses between contiguous particles are so minimized as to preclude the formation of eddies in the liquid in the tank, said last mentioned means comprising a plurality of angularly divergent and nonparallel substantially concentric axially spaced nested truncated conical guiding members discharging into a common concentric angular conduit comprising said entrance and communicating with the means for circulating the liquid.

13. A mixing system for liquids which comprises a receptacle for the liquids, means for circulating liquid at a high rate of ow from an entrance at one `part of the receptacle to discharge into another part thereof, means for securing relatively slow differential flows in the liquids in the tank passing toward said entrance to the circulating means whereby shearing stresses between contiguous particles are so minimized as to preclude the formation of eddies in the liquid in the tank, and means in the entrance for converting the slow velocities of flow in the receptacle into high velocity flow in the circulating means only, said last mentioned means comprising a plurality of angularly divergent and non-parallel substantially concentric axially spaced nested truncated conical guiding members discharging into a common concentric angular conduit comprising said entrance and communicating with the means for circulating the liquid.

GEORGE G. SCHMIDT.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 563,630 Webster July 7, 1896 1,580,476 Fassio Apr. 13, 1926 1,676,511 Wood July 10, 1928 1,897,953 Dehle Feb. 14, 1933 1,909,487 Cowles May 16, 1933 FOREIGN PATENTS Number Country Date 103,488 Great Britain Jan. 5, 1917 696,680 France Jan. 6, 1931 

